ostline



July 2, 1929, J. E. OSTLINE TELEPHONE SYSTEM Original Filed Nov. 1. 1924 ITLUEHZUP Juhn E. UEIZmE Patented July 2, 1929,,

PATENT OFFICE.

JOHN E. OSTLINE, OF LIVERPOOL, ENGLAND, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

AUTOMATIC ELECTRIC INC, OF CHICAGQ ILLINOIS, A. CORPORATION OF DELA- WARE.

TELEPHONE SYSTEM.

A'pplication filed November 1, 1924, Serial No. 747,374, and in Great Britain December 12, 1923. Renewed November 23, 1928.

i The present invention concerns improvements in or relating to telephone systems and more particularly concerns systems employing switches which move always in the same direction such as for instance, rotary line switches which are individual to a subscribers line and are used for extending connections to an idle first numerical switch.

In one construction of switches of this type, the movable contacts or wipers each consist of a pair of springy metal members separated at the axis of rotation by a washer and with their ends turned in so as to engage the fixed or bank contacts on both sides and thus grip them. Since the wipers of these switches always move in the same direction, connection to them must be made by rubbing or brushing contacts. The usual method employed with the above construction is to provide feed wipers comprising two additional springy members with their ends turned outwards so as to bear upon the inside of the con necting wipers close to the axis, these feed wipers being in contact at the end remote from the axis so that they occupy about the thickness of an ordinary fixed contact and are thus easily passed over by the moving wipers. f The object of the present invention is to enable the number of wipers used in switches of the type described to be reduced and thisis achieved by arranging that the feed wipers are not in contact at the end corresponding to the bank contacts but are separated by insulating material so that each may be used in a separate circuit. The rotating wipers will also now be insulated from one another by washers or the like and in general it will now be desirable to split the fixed contacts also. If this is done, the same connecting facilities may be obtained from a switch by the use of only half the number of wipers previously employed.

This principle may be-applied with particular advantage to the case of rotary line switches having a home or normal position to which they return on release. The provision of a normal position for switches of this type is intended to allow of more economical trunking by the use of grading and also to overcome a defect sometimes experienced with switches which remained on the contacts corresponding to the normal position. In this case, however, it is possible to combine this circuit and thenormal test circuit so that normal solid contacts may be used in all positions except the normal one and only one contact need be split. Thus, according to the invention a pair of moving contacts insulated from one another are adapted to engage a common fixed contact except in the normal position of the switch. The application of the invention to a subscribers line switch will be better understood from the following description, reference being had to the accompanying drawing.

Consider first the case of an outgoing call. When the subscriber removes his receiver, a circuit is completed over his'loop and line conductors 1 and 2 for the line relay 4. Upon operating, relay 4 at armature 5 connects earth to private normal conductor 3 so as to busy the line in the banks of the connectors and at armature 6 completes the following stepping circuit: earth, armature 5 and its front contact, front contact and armature 6, lower split contact 21 in the normal position, lower split wiper 15, armature 13 and its back contact, interrupter contact 9, stepping magnet 8 to battery. The connection of earth to conductor 3 also completes a circuit for switching relay 7 and stepping magnet 8 in series, butv since relay 7 is short circuited by the circuit traced-above it cannot operate. Magnet 8, however, operates to advance the wipers 15-19, inclusive, into engagement with the next set of contacts, so that the wipers 15 and 16 now engage the first solid contact similar to 22. If the associated trunk line is busy therewill be earth on contact 22 and magnet 8 will be again operated. This continues until wiper 15 engages a contact whichis not earthed whereupon relay 7 energizes in series with magnet 8 which is not now operated.

Relay 7 at armature'll prepares the metering circuit, at armature 12 opens another point in the circuit for restoring the switch to normal, at armature 13 prepares a locking circuit for itself and at armatures 10 and 14 disconnects line relay 4 and-earth and-connects the speakingleads' through. Linerelay 4 thereupon deenergizes but as it is slow to release, earth for maintaining relay 7 operated is fed back from the switch ahead before armature 5- calling party hangs up, earth is removed from release trunk-conductor similar to26 and relay 7 is therefore deenergized. A circuit is now completed as follows: earth, armature 5 and its back contact, armature 12 and its back contact, upper split wiper 16,. contact on which it is resting, lower split Wiper 15, arma: ture 13 and its back-contact, interrupter contact 9, stepping magnet 8 to battery. The wipers are thus stepped around until wipers 15 and 16 reach the split contact in the home position when the aboveicircuit is opened and the stepping magnet can only be again connected up whenv the line relay is againoperatedf For incoming calls, earth is connected toinormal conductor3 and relay 7 isoperated. Since, however, all the wipers are resting on dead contacts, .no connectioncan be made to an outgoing trunk and .the only purpose serves is the, disconnection of battery and earth from the trunk conductors.

Having now particularlydescribed and ascertained the nature of my, invention and in what manner the same is to be performed, I deelarethat what I claimis:

1. In a selector switch having a normal position, a pair of moving contacts'insulated from each other, a common fixed contact adapted .to be engaged by both-said moving contacts, .a test circuitfor said switch including one of said moving contacts andsaid common fixed-contact, and a'circuit for restoring said switch to normal including ,the otherof said moving contacts and said common fixed contact. i 5 7 2. In a selector switch having a-normal position, apair of moving contacts insulated from each other, a common fixed contact adapted to be engaged by both said moving contacts, a 'testcircuit'for said switch including one of said moving contacts and said common fixed contact, and a circuit "for retacts in'another position circuit arrangements including said first fixed contact and said one [of said moving contacts for moving said switchfrom its normal position to said other position, and other circuit, arrangements in cluding both said moving contacts and said second fixed contact to restore said switch to its normal position.

4. In a rotary line switch, trunk line contacts, a home position contact, a test wiper, means including a circuit extending through said wiper and said home position contact for enabling the switch to start hunting, means including a circuit through said wiper and busy trunk contactsfor continuing the hunting operation until an idle contact is found, a second wiper engaging the same trunk contacts as said test wiper, and a circuit including said test wiper and said second wiper in series for causing the switch to resume its movement and continue same until said wiper reaches said home contact again.

5. In a rotary line switch having a normal position, a test wiper, a second wiper, test contacts, each contact engaged by both said ipers, circuit arrangements including said test wiper and said test contacts for operat ing said switch to find an idle trunk, other circuit arrangements including said test wiper, said test contacts, and said second wiper in series of operating said switch to return to its normal position.

6. Ina selector switch, a pair of moving contacts insulated from each other,'a contact engaged by both said moving contacts when the switch is in an operated position and a second contact engaged by only one of said moving contacts when the switch is'in its normal position.

V 7. In a selector switch, a pair of moving contacts insulated from, each other, a contact engaged by both said moving contacts when the switch is in an operated position and two other contacts insulated from-each other and engaged by the said two moving contacts, respectively, when the switch is inits normal position.

8. In a lineswitch of the homing type, a line relay, a switching relay, a motor magnet, a test wiper, a trunk hunting circuit for the magnet including said test wiper and aback contact of the switching relay, and a homing circuit for the magnet including said back contact, said test, wiper, and a second back contact of the switching relay in series.

9. In a lineswitch of the homingtype, a line relay, a switching relay, a motor magnet, a

trunk hunting wiper having a home position contact, a circuit for the magnet for initiating the trunk hunting movement of the switch said circuit being controlled over said wiper and the home contact of the switch and including a back contact on the switching relay and a front contact on the line relayin series, and a homing circuit for the magnet including said wiper, said back contact of said switching relay, and a back contact of the line relay in series.

10. In a lineswitch of the homing type, a line relay, a switching relay, a motor magnet, a trunk hunting circuit for the magnet effective when the switch is in the home posi tion, said circuit including a back contact of the switching relay and a front contact of the line relay, and a homing circuit for the magnet including said back contact of the switching relay, and a second back contact of the switching relay in series.

11. In a lineswitch of the homing type, a line relay, a switching relay, :1 motor magnet, a trunk hunting circuit for the magnet efi ective when the switch is in. the home position, said circuit including a back contact of the switching relay and a front contact of the line relay in series, and a homing circuit tor the magnet including a back contact on the switching relay and a back contact 011 the line relay in series.

12. In a selector switch having a home position, two wipers insulated from each other, a circuit including one of said. wipers for starting said switch, and a circuit including the other of said wipers for restoring said switch.

13. In a telephone system, a rotary line switch of the homing type, means for causing the rotary movement of the switch, a cut oil relay eilective it operated to stop the rotary movement, and means entirely within the switch for rendering the cut off relay inoperative during the home returning movement of the switch.

14. A selector switch for connecting a subscribers telephone line to an idle outgoing trunk line, in which a pair of insulated wipers are adapted to engage a common fixed contact except in a particular position where they engage separate contacts, and in which the normal test circuit extends over one of said wipers while the circuit for restoring the switch to normal includes the other.

15. In a selector switch, a pair of wipers insulated from each other, a row of fixed contacts, each contact consistingof a single metallic member adapted to be engaged by one of said wipers on one side and by the other of said wipers on the other side, and two separate contacts adapted to be engaged by said wipers, respectively, in a particular position.

16. In a selector switch, a pair of wipers insulated from each other, a row of fixed con tacts, each contact consisting of a single 1netallic member adapted to be engaged by one oitsaid wipers on one side and by the other of said wipers on the other side, and another contact in the row insulated on one side so that onlyone of said wipers may engage the same.

17. A subscribers individual line switch comprising a cut-01f relay operated when the line is called, means for operatingsaid switch to extend a call, means for making the line busy to other calls, means for returning the switch to normal at the end of the call, means for removing the busy condition when the return movement starts, and means for preventing the operation of said cut-oflI' relay if the line is called before the return movement is completed.

18. In a trunk hunting switch having a home position, a switching relay energized responsive to the switch seizing an idle trunk, means for deenergizing said relay to cause said switch to return to its home position and to cause said switch to test idle to incoming calls, and means for preventing the operation of said relay responsive to the selection of said switch on an incoming call during the homing movement of said switch.

19. In a trunk hunting switch having a home position, a switching relay energized responsive to the switch seizing an idle trunk, an incoming test conductor, contacts on said relay closed by its energization for applying a. guarding potential to said test conductor, means for deenergizing said relay to cause an automatic movement of said switch to its normal position and to cause said contacts to remove the guarding potential from said test conductor, and means for preventing the operation of said relay responsive to the selection of said switch on an incoming call during the homing movement of said switch.

20. In a rotary line switch of the homing type, an incoming test conductor, means for placing a guarding potential on said conductor to prevent seizure of the switch during its use, a circuit normally connecting an idle potential to said conductor to permit the seizure of the switch'when it is in home position and not in use, and means for placing a neutralizing potential on said conductor during the homing operation of said switch to render the switch unguarded and selectable but not seizable until it reaches its home position.

21. In a rotary line switch of the homing type, a switching relay, a magnet, one terminal of the relay being connected to a terminal of the magnet, an incoming test conductor being connected to the other terminal of said mentioned potential and for reapplying said second-mentioned. potential to causethe return-to-norlnal movement of the switch, whereby during said movement the switch is unguarded and selectable but not seizable.

22. In a rotary line switch of the homing type, a line relay, a cut-off relay, an operating circuit and aholding' circuit for said cut-ofi' relay closed successively during the establishment vo1? an outgoing call, a third'circuit for said cut ofi relay completedduring the establishment of an incoming call, and oil'- norinal contacts for renderingsaid third'circuit ineffective during the home returning movement of the switch.

Signed by me at Liverpool, England, this 9th day of October, 1924.

- JOHN E. OSTLINE. 

